Water pump-propelled boats or “jet boats” are well-known in the art. In this regard, such boats comprise a normal boat fitted with an engine to drive a water pump or “jet unit” that draws water from an intake formed in the bottom of the boat and thereafter discharges the water through the transom of the boat at a high velocity. To achieve that end, the jet unit typically is provided with an impeller and stator which increases the pressure of the water flow drawn in from the intake and discharges the same via a nozzle formed at the back of the jet unit as a high velocity jet stream. The jet unit is propelled by a jet-drive motor, which typically comprises a conventional motor having a driveshaft attached via a coupling formed upon the jet unit to turn the impeller.
The design features typically incorporated in most jet boats have several advantages over most other forms of marine propulsion, such as stern drives, outboard motors, shafted propellers and the like. Among such advantages include substantially greater safety insofar as water jet propulsion does not incorporate the use of an exposed propellers, which are known to cause substantial injury. Additionally, the lack of exposed propeller eliminates impact damage or snags that can occur with protruding propulsion gear, as well as substantially reduces hull resistance insofar as the jet intake is generally flush with the hull bottom. Moreover, jet boats are widely considered to be highly efficient, operate smooth and quietly, and able to maximize engine life insofar as engine overload utilizing water jet propulsion is nearly impossible.
Despite such advantages, however, substantial drawbacks still exist with respect to the design of most jet units incorporated within most jet boats. In this regard, virtually all water jet systems incorporate the use of a single jet unit driven by a single engine. In such arrangement, the performance of the boat is limited by the jet unit generating the water jet propulsion. Indeed, such drawbacks continue to exist despite substantial advances that have been made in jet unit design.
As a consequence, virtually all jet boats currently in use, despite the engine capacity to do so, suffer from suboptimal fuel efficiency, lesser responsiveness, and lesser ability to pull heavier loads than could be attained if the water jet propulsion generated by the jet unit were commensurate with engine capacity. Such, despite its potential to be the most advantageous form of marine propulsion, water jet propulsion is deemed only the equivalent or at best only slightly more advantageous than other forms of propulsion, and in particular outboard propeller systems and the like.
Accordingly, there is a substantial need in the art for a system by which jet stream velocity and intensity can be maximized in a water jet propulsion system to thus enable a jet boat to exhibit faster speeds, greater performance, enhanced fuel efficiency, and the ability to pull heavier loads, especially at lower engine RPM's. There is additionally a need for such a system whereby the water intake and discharge can be maximized in a water jet propulsion system that is substantially greater than prior art systems and methods. Still further, there is a need in the art for such a system that is relatively inexpensive, can be readily incorporated into the production of new boats, can be configured as a retrofit for installation for existing boats, and can be constructed utilizing conventional water jet propulsion componentry.